Using Water Jet Machining, A jet of water to cut a sheet of metal may sound impossible, but it is actually based on the principle we learn early in our lives.
A simple example is of Water Jet is- When a finger is put over part of the tap, the stream of water flows with higher pressure so that it washes away mud far more effectively, giving a jet-cleaned item.
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What is Water Jet Machining?
A Non-conventional machining process In which a high-velocity water jet is used to remove materials from the surface of the workpiece.
Water jet machining(WJM) is a mechanical energy based non-traditional machining process used to cut and machine soft and non-metallic materials.
It uses the high-velocity water jet to cut a non-metallic workpiece smoothly.
However, It is just similar to Abrasive jet machining.
Working Principle of water jet machining-
It works on the principle of water erosion.
When a high-velocity water jet strikes the surface, the removal of metal takes place.
Types of water jet machining-
There are basically two types of water jet machining-
- Water Jet cutting
- Abrasive Jet Cutting
(I) Water Jet Cutting–
It is the type of machining that uses only water jet force to cut soft or non-metallic materials like wood and plastics. Rubber, foam, paper, cloths and foods.
Here is the Water jet cutting thickness, which can be considered during operation-
(II) Abrasive water jet machining–
Abrasive water jet cutting is the type of machining where abrasives are used to increase the cutting power of machining.
Adding abrasives with a water jet gives the ability to cut hard materials.
Through this abrasive water jet machining process, Hard materials like- titanium, steel, aluminium can be easily cut down.
Abrasive materials used-
The abrasives used in abrasive water jet machines are- Garnet, aluminium oxide(Al₂O₃), glass, sand.
This raises the force to cut and makes it able to cut harder materials.
Parts and construction-
Various part is used to construct the Water jet machine-
- Storage tank
- Control valve
- Drain System
(I) Storage Tank-
The storage tank is also called a reservoir, which stores the water inside it and acts as permanent water storage.
The pump is used to connect the storage tank to the intensifier.
An intensifier is used to intensify the liquid pressure. In general, It increases the pressure of water and gives a high-pressure water jet.
Water pressure is used for cutting is- 200-400mPa or can be varied according to the workpiece.
High-pressure tubing is used to transport fluid from one system component to another system component.
The tubing may be made from a solid stainless steel wall or composite wall with stainless steel inside and carbon steel as a jacket.
Tubing may be used to pressurize fluids at a pressure greater than the yield stress of the tube material.
The accumulator is the support system of the reservoir, Where water is stored in the accumulator temporarily.
This temporary water may be used, in case of reservoir failure.
(VI) Control valve-
a control valve is used to control the flow and direction of the water jet.
Nozzle meant to convert the high-pressure liquid to a high-velocity jet. Hence, pressure energy is converted into kinetic energy through the nozzle and water hits the workpiece with intensify pressure.
For the minimum erosion, the Material should be extremely hard. Nozzle made of sintered diamond or sapphire is used.
Diamond, tungsten carbide and special steel are also used to make nozzles.
The diameter of a nozzle is usually 0.05-0.35mm.
Fig- Systematic diagram of Nozzle
The flow regulator is used to regulate the flow of the water jet.
(IX) Drain System-
When the water jet goes through cutting, it mixed up some wear and tear particles into the water, makes it unable to reuse. Then, the Drain system comes into play. It cleans the water and makes it reusable and sends it to the storage tank.
Working of Water Jet Machining-
- Initially, water from the reservoir is pumped to the intensifier using a hydraulic pump.
- Instifier increases the pressure of water up to 200-400mPa.
- An excess supply of water sends to the accumulator for temporary storage.
- Then the required quantity of pressurized water enters the nozzle through a control valve and flow regulator.
- In case you missed it, the Control valve controls the direction of the water. flow regulator controls and regulate the flow of water and the nozzle converts the pressure energy of water into kinetic energy of water having very high velocity, approx 900m/s.
- When a water jet strikes with very high velocity, it induces a trace on the workpiece.
- These induced traces further intensify, causing the removal of material for the workpiece.
Fig.- Systematic diagram of Water machining process-
Various water jet machining process parameters are given below-
- Standoff distance
- Fluid pressure
- Feed rate
- Jet fluid
- Nozzle diameter
It is the gap between the jet nozzle and the workpiece.
Material removal increases with the increase of stand-off distance up to a certain limit and then falls gradually.
Its values normally lie between 3-25mm.
Cutting at a higher water jet is faster and increased pressure increasing the depth of the cut.
Thick materials can be machined without difficulty at high jet pressure and low feed rate.
It must have low viscosity, minimized energy use, common and inexpensive.
The internal diameter of the nozzle ranges from 0.07-0.50mm.
Nozzle material should be wear-resistant and easily maintain.
The various advantages of WJM are-
- Excellent precision
- Water is cheap, non-toxic, readily available and can be easily disposed of.
- Water jet approaches the ideal single point tool.
- The process gives a clean and sharp cut.
- Unlike the conventional machining process, this method does not generate heat.
- Best suited for the explosive environment.
- Noise is minimized as the power units and pumps can be kept away from the cutting point.
- No moving parts, therefore, less maintenance is required.
- Jet takes away all the cutting residue and hence there is no pollution problem, ie, Eco-friendly.
- Water can be re-used by filtering solids.
- Only a small amount of fluid is required, approx 100-150 litres/hour.
The various disadvantages of WJM are-
- Only soft materials can be machined.
- Very high thick materials can not be machined easily.
- The initial cost is high
- Not suitable for mass production.
The various Applications of WJM is-
- Useful for cutting materials that are porous, fibrous, granular, or soft. It includes the materials like corrugated board, rubber, granite, plywood, glass, aluminium.
- To cut wood, ceramics, composites, leather, foam, wire stripping and deburring.
- In aerospace and other similar industries, a water jet is cut off asbestos to minimize airborne dust in the atmosphere.
- Used to cut fibreglass and polyethene automotive parts.
⇒This video of Water jet machining will blow your mind, and you will mesmerise yourself by seeing the power of water. Please Give a watch–
Over the past three decades, due to the potential for reducing dust and associated hazards while cutting coal or rock using water jet machining.
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Here is your water jet machining pdf-
Q. Can a water jet kill you?
Ans. No, it can not kill you but it can cause life-threatening problems to you because the very high force of water hits you.
Q. Is water jet cutting expensive?
Ans. Yes, water jet cutting is expensive to use and maintain also.
Q. How accurate is water jet cutting?
Ans. Water jet cutting is generally very accurate and its tolerance range is close to 0.001inch, considered high accuracy range.
Abhishek Tiwary is a blogger by passion and a Quality Engineer by profession. He has completed his B.Tech degree in the year of 2017. Now working in a reputed firm and He loves to share his knowledge with others.